Levels of adenosine deaminase, AMP deaminase, and adenylate kinase in cultured human lymphoblast lines: Exquisite sensitivity of AMP deaminase to adenosine deaminase inhibitors

Purine Metabolizing Enzymes of Lymphocyte Cell Populations: Correlation between AMP-Deaminase Activity and dATP Accumulation in Murine Lymphocytes

“…The B and null cell lines studied, which derive from normal cells, are considered as mature cells with low terminal deoxynucleotidyltransferase (TdT) activity ( 12), while T-ALL lymphoblasts display high TdT levels which reflect early stages of maturation. Our results agree with those of Fishbein (9) and suggest that AMP-DA, like ecto-5" and unlike ADA, increases during cell differentiation (Table 11).…”

“…The enzyme form(s) present in immature thymocytes poorly deaminates dAMP and is highly inhibited by deoxycoformycin, unlike that present in mature T cells. Such a differenze in deoxycoformycin sensitivity has been reported for the enzymes expressed in T-ALL and B or null lymphoblastoid cell lines (9).…”

“…Contrary to other enzymes of nucleotide metabolism, these enzymes have scarcely been studied in lymphoid cells. It was only reported that T lymphoblasts display AMP-DA activities 5to 10-fold lower than those of B lymphoblasts and that different AMP-DA isoenzymes could be expressed in these lymphoblasts (9). It was also shown that AMP-DA activity is greatly altered during the in vitro differentiation of muscle cells (10).…”

“…Fishbein reported that this enzyme, involved in nucleotide metabolism, was not uniformly distributed among human lymphoblastoid cell lines (9). Bagnara et al (24) suggested that AMP-DA could be involved in the deoxyadenosine-induced ATI' depletion in deoxycoformycin-treated T lymphoblast, however, this event occurs a lon:; time after dATP accumulation has reached its optimum.…”

Purine Uptake and Release in Rat C6 Glioma Cells

“…The effects of the nucleoside transport inhibitors DPR (1 n M ‐30 μ M ) and NBMPR (1 n M ‐30 μ M ) on 3 H‐purine release were tested. In addition, the contribution of specific enzymes to the metabolism and release of 3 H‐purines was examined using 1 μ M EHNA to inhibit adenosine deaminase, 100 μ M EHNA to inhibit both adenosine deaminase and AMP deaminase (Fishbein et al, 1981), and 10 μ M BCX‐34 to inhibit purine nucleoside phosphorylase (PNP) (Jurkowitz, et al, 1998). In some experiments cells were treated with IAA and NaCN and then washed and returned to Na + buffer to mimic a return to normoxic conditions.…”